<?php

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/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package		CodeIgniter
 * @author		ExpressionEngine Dev Team
 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc.
 * @license		http://codeigniter.com/user_guide/license.html
 * @link		http://codeigniter.com
 * @since		Version 1.0
 * @filesource
 */

// ------------------------------------------------------------------------


/**
 * MS SQL Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the active record
 * class is being used or not.
 *
 * @package		CodeIgniter
 * @subpackage	Drivers
 * @category	Database
 * @author		ExpressionEngine Dev Team
 * @link		http://codeigniter.com/user_guide/database/
 */
class CI_DB_mssql_driver extends CI_DB {
	
	var $dbdriver = 'mssql';
	
	// The character used for escaping
	var $_escape_char = '';
	
	// clause and character used for LIKE escape sequences
	var $_like_escape_str = " ESCAPE '%s' ";
	var $_like_escape_chr = '!';
	
	/**
	 * The syntax to count rows is slightly different across different
	 * database engines, so this string appears in each driver and is
	 * used for the count_all() and count_all_results() functions.
	 */
	var $_count_string = "SELECT COUNT(*) AS ";
	var $_random_keyword = ' ASC'; // not currently supported
	

	/**
	 * Non-persistent database connection
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_connect() {
		if ($this->port != '') {
			$this->hostname .= ',' . $this->port;
		}
		
		return @mssql_connect ( $this->hostname, $this->username, $this->password );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Persistent database connection
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_pconnect() {
		if ($this->port != '') {
			$this->hostname .= ',' . $this->port;
		}
		
		return @mssql_pconnect ( $this->hostname, $this->username, $this->password );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Reconnect
	 *
	 * Keep / reestablish the db connection if no queries have been
	 * sent for a length of time exceeding the server's idle timeout
	 *
	 * @access	public
	 * @return	void
	 */
	function reconnect() {
		// not implemented in MSSQL
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Select the database
	 *
	 * @access	private called by the base class
	 * @return	resource
	 */
	function db_select() {
		// Note: The brackets are required in the event that the DB name
		// contains reserved characters
		return @mssql_select_db ( '[' . $this->database . ']', $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Set client character set
	 *
	 * @access	public
	 * @param	string
	 * @param	string
	 * @return	resource
	 */
	function db_set_charset($charset, $collation) {
		// @todo - add support if needed
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Execute the query
	 *
	 * @access	private called by the base class
	 * @param	string	an SQL query
	 * @return	resource
	 */
	function _execute($sql) {
		$sql = $this->_prep_query ( $sql );
		return @mssql_query ( $sql, $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Prep the query
	 *
	 * If needed, each database adapter can prep the query string
	 *
	 * @access	private called by execute()
	 * @param	string	an SQL query
	 * @return	string
	 */
	function _prep_query($sql) {
		return $sql;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Begin Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_begin($test_mode = FALSE) {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		// Reset the transaction failure flag.
		// If the $test_mode flag is set to TRUE transactions will be rolled back
		// even if the queries produce a successful result.
		$this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;
		
		$this->simple_query ( 'BEGIN TRAN' );
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Commit Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_commit() {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		$this->simple_query ( 'COMMIT TRAN' );
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Rollback Transaction
	 *
	 * @access	public
	 * @return	bool
	 */
	function trans_rollback() {
		if (! $this->trans_enabled) {
			return TRUE;
		}
		
		// When transactions are nested we only begin/commit/rollback the outermost ones
		if ($this->_trans_depth > 0) {
			return TRUE;
		}
		
		$this->simple_query ( 'ROLLBACK TRAN' );
		return TRUE;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Escape String
	 *
	 * @access	public
	 * @param	string
	 * @param	bool	whether or not the string will be used in a LIKE condition
	 * @return	string
	 */
	function escape_str($str, $like = FALSE) {
		if (is_array ( $str )) {
			foreach ( $str as $key => $val ) {
				$str [$key] = $this->escape_str ( $val, $like );
			}
			
			return $str;
		}
		
		// Escape single quotes
		$str = str_replace ( "'", "''", remove_invisible_characters ( $str ) );
		
		// escape LIKE condition wildcards
		if ($like === TRUE) {
			$str = str_replace ( array ($this->_like_escape_chr, '%', '_' ), array ($this->_like_escape_chr . $this->_like_escape_chr, $this->_like_escape_chr . '%', $this->_like_escape_chr . '_' ), $str );
		}
		
		return $str;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Affected Rows
	 *
	 * @access	public
	 * @return	integer
	 */
	function affected_rows() {
		return @mssql_rows_affected ( $this->conn_id );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Insert ID
	 *
	 * Returns the last id created in the Identity column.
	 *
	 * @access public
	 * @return integer
	 */
	function insert_id() {
		$ver = self::_parse_major_version ( $this->version () );
		$sql = ($ver >= 8 ? "SELECT SCOPE_IDENTITY() AS last_id" : "SELECT @@IDENTITY AS last_id");
		$query = $this->query ( $sql );
		$row = $query->row ();
		return $row->last_id;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Parse major version
	 *
	 * Grabs the major version number from the
	 * database server version string passed in.
	 *
	 * @access private
	 * @param string $version
	 * @return int16 major version number
	 */
	function _parse_major_version($version) {
		preg_match ( '/([0-9]+)\.([0-9]+)\.([0-9]+)/', $version, $ver_info );
		return $ver_info [1]; // return the major version b/c that's all we're interested in.
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Version number query string
	 *
	 * @access public
	 * @return string
	 */
	function _version() {
		return "SELECT @@VERSION AS ver";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * "Count All" query
	 *
	 * Generates a platform-specific query string that counts all records in
	 * the specified database
	 *
	 * @access	public
	 * @param	string
	 * @return	string
	 */
	function count_all($table = '') {
		if ($table == '') {
			return 0;
		}
		
		$query = $this->query ( $this->_count_string . $this->_protect_identifiers ( 'numrows' ) . " FROM " . $this->_protect_identifiers ( $table, TRUE, NULL, FALSE ) );
		
		if ($query->num_rows () == 0) {
			return 0;
		}
		
		$row = $query->row ();
		return ( int ) $row->numrows;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * List table query
	 *
	 * Generates a platform-specific query string so that the table names can be fetched
	 *
	 * @access	private
	 * @param	boolean
	 * @return	string
	 */
	function _list_tables($prefix_limit = FALSE) {
		$sql = "SELECT name FROM sysobjects WHERE type = 'U' ORDER BY name";
		
		// for future compatibility
		if ($prefix_limit !== FALSE and $this->dbprefix != '') {
			//$sql .= " LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
			return FALSE; // not currently supported
		}
		
		return $sql;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * List column query
	 *
	 * Generates a platform-specific query string so that the column names can be fetched
	 *
	 * @access	private
	 * @param	string	the table name
	 * @return	string
	 */
	function _list_columns($table = '') {
		return "SELECT * FROM INFORMATION_SCHEMA.Columns WHERE TABLE_NAME = '" . $table . "'";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Field data query
	 *
	 * Generates a platform-specific query so that the column data can be retrieved
	 *
	 * @access	public
	 * @param	string	the table name
	 * @return	object
	 */
	function _field_data($table) {
		return "SELECT TOP 1 * FROM " . $table;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * The error message string
	 *
	 * @access	private
	 * @return	string
	 */
	function _error_message() {
		return mssql_get_last_message ();
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * The error message number
	 *
	 * @access	private
	 * @return	integer
	 */
	function _error_number() {
		// Are error numbers supported?
		return '';
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Escape the SQL Identifiers
	 *
	 * This function escapes column and table names
	 *
	 * @access	private
	 * @param	string
	 * @return	string
	 */
	function _escape_identifiers($item) {
		if ($this->_escape_char == '') {
			return $item;
		}
		
		foreach ( $this->_reserved_identifiers as $id ) {
			if (strpos ( $item, '.' . $id ) !== FALSE) {
				$str = $this->_escape_char . str_replace ( '.', $this->_escape_char . '.', $item );
				
				// remove duplicates if the user already included the escape
				return preg_replace ( '/[' . $this->_escape_char . ']+/', $this->_escape_char, $str );
			}
		}
		
		if (strpos ( $item, '.' ) !== FALSE) {
			$str = $this->_escape_char . str_replace ( '.', $this->_escape_char . '.' . $this->_escape_char, $item ) . $this->_escape_char;
		} else {
			$str = $this->_escape_char . $item . $this->_escape_char;
		}
		
		// remove duplicates if the user already included the escape
		return preg_replace ( '/[' . $this->_escape_char . ']+/', $this->_escape_char, $str );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * From Tables
	 *
	 * This function implicitly groups FROM tables so there is no confusion
	 * about operator precedence in harmony with SQL standards
	 *
	 * @access	public
	 * @param	type
	 * @return	type
	 */
	function _from_tables($tables) {
		if (! is_array ( $tables )) {
			$tables = array ($tables );
		}
		
		return implode ( ', ', $tables );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Insert statement
	 *
	 * Generates a platform-specific insert string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the insert keys
	 * @param	array	the insert values
	 * @return	string
	 */
	function _insert($table, $keys, $values) {
		return "INSERT INTO " . $table . " (" . implode ( ', ', $keys ) . ") VALUES (" . implode ( ', ', $values ) . ")";
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Update statement
	 *
	 * Generates a platform-specific update string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the update data
	 * @param	array	the where clause
	 * @param	array	the orderby clause
	 * @param	array	the limit clause
	 * @return	string
	 */
	function _update($table, $values, $where, $orderby = array(), $limit = FALSE) {
		foreach ( $values as $key => $val ) {
			$valstr [] = $key . " = " . $val;
		}
		
		$limit = (! $limit) ? '' : ' LIMIT ' . $limit;
		
		$orderby = (count ( $orderby ) >= 1) ? ' ORDER BY ' . implode ( ", ", $orderby ) : '';
		
		$sql = "UPDATE " . $table . " SET " . implode ( ', ', $valstr );
		
		$sql .= ($where != '' and count ( $where ) >= 1) ? " WHERE " . implode ( " ", $where ) : '';
		
		$sql .= $orderby . $limit;
		
		return $sql;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Truncate statement
	 *
	 * Generates a platform-specific truncate string from the supplied data
	 * If the database does not support the truncate() command
	 * This function maps to "DELETE FROM table"
	 *
	 * @access	public
	 * @param	string	the table name
	 * @return	string
	 */
	function _truncate($table) {
		return "TRUNCATE " . $table;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Delete statement
	 *
	 * Generates a platform-specific delete string from the supplied data
	 *
	 * @access	public
	 * @param	string	the table name
	 * @param	array	the where clause
	 * @param	string	the limit clause
	 * @return	string
	 */
	function _delete($table, $where = array(), $like = array(), $limit = FALSE) {
		$conditions = '';
		
		if (count ( $where ) > 0 or count ( $like ) > 0) {
			$conditions = "\nWHERE ";
			$conditions .= implode ( "\n", $this->ar_where );
			
			if (count ( $where ) > 0 && count ( $like ) > 0) {
				$conditions .= " AND ";
			}
			$conditions .= implode ( "\n", $like );
		}
		
		$limit = (! $limit) ? '' : ' LIMIT ' . $limit;
		
		return "DELETE FROM " . $table . $conditions . $limit;
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Limit string
	 *
	 * Generates a platform-specific LIMIT clause
	 *
	 * @access	public
	 * @param	string	the sql query string
	 * @param	integer	the number of rows to limit the query to
	 * @param	integer	the offset value
	 * @return	string
	 */
	function _limit($sql, $limit, $offset) {
		$i = $limit + $offset;
		
		return preg_replace ( '/(^\SELECT (DISTINCT)?)/i', '\\1 TOP ' . $i . ' ', $sql );
	}
	
	// --------------------------------------------------------------------
	

	/**
	 * Close DB Connection
	 *
	 * @access	public
	 * @param	resource
	 * @return	void
	 */
	function _close($conn_id) {
		@mssql_close ( $conn_id );
	}

}



/* End of file mssql_driver.php */
/* Location: ./system/database/drivers/mssql/mssql_driver.php */